Many devices have been developed to assist a golfer to improve his or her swing. Swing theories tend to describe and materialize the golf swing as a wheel, the axis being the golfer's neck and the rim being at the ball. The club, or simulated club, slides backward on the rim or on a plane parallel to the radius of the wheel, up to the top of the swing. At this point, there is a re-route of the club head, described as a "loop"; then, the downward swing follows the same path, parallel to the rim or to the radius of the wheel. According to golf instructors, such loop is necessary to promote a squared club face at impact on the target line. During the follow-through and finish, the club continues the same process.
Another important feature is the action of the hands. In a correct right-handed golf swing, the left hand "climbs" over the right hand on the backswing (pronation) to finish at the top in a position known as the tray position. On the downswing, it reverses, the right hand "climbing" over the left hand (supination). Depending on golf instructors, beliefs, this should be done with or without alteration of the angle at the back of the wrist, formed by the left forearm and the hand.
In order to achieve one of the above features or both, many devices have been developed with or without attachments.
Canadian patent No. 518,637 of Plunkett issued Nov. 15, 1955 describes a device without an attachment, the club bearing on guides to control the orientation and position of the club face when swung.
Various devices have been developed with an attachment wherein a line or a rope is anchored to an immoveable object at one end and is attached and secured at the other end to part of a golf club: see, for example, Canadian patent No. 872,391 of Gentry issued Jun. 1, 1971.
A more recent patent, Canadian patent No. 1,185,633 issued Apr. 16, 1985 to Kane et al , describes a golfer practice swing device which uses an elongated rigid rod and a clamp which engages the shaft of a golf club by gripping a portion thereof to secure against unpurposeful disengagement. Connection means are associated with the clamp to mechanically connect the clamp to the rod for pivotal movement of the clamp and the shaft with respect to the rod about an axis parallel to that of the shaft. The length of the rod is such that, when the device is in use, the shaft will be guided towards a proper swing plane and will be turned a require amount for pronation and supination. Consequently, the head of the club will be guided towards a proper swing path. Hence, with this device, the golfer is forced to swing in a predetermined golf swing path.
There are two important elements in a golf swing: the plane and the arc. Referring to the above described "wheel" swing, the rim is the arc (which is the path of travel of the club head) and the radius is the plane. It has been established, through computer analysis, that, in a reasonable proper swing, the arc should not be shortened during the backswing but, on the downswing, it must slightly shorten and move to the left (for a right-handed golfer). The plane and its angle is dictated by two elements: the golfer's club (known as the shaft plane) and the golfer's own physical aptitudes. Hence, a golfer has his or her "own swing plane" and there are as many swing planes as there are golfers.
Hence, the concept of a swing being a wheel needs to be carefully revised.
Because of the loop created at the top of the swing, due to a change of direction and weight transfer, the golfer creates a second path or a "second wheel" which is above the one created during the backswing. These "wheels" meet at the bottom but separate at the top. In other words, the downswing is slightly above the backswing. This promotes and encourages a position, known as the delay, which consists in keeping the club head away from the ball as long as possible. After impact, as the golfer turns his or her body to the left and begins to raise, he or she also turns and moves the axis of the wheel and the rim (right to left, down to up); it also slides slightly to the left. This means that the epicenter of the swing moves constantly during the swing.
Referring to the devices described above and others which tend to materialize these concept, none describes and achieves all the movements in a very simple and efficient device. If the action of the hands is an important aspect of the teaching, then the plane and the arc remain constant factors of a swing. If the concept is that of a hoop, it should be able to move constantly right to left, up and down in order to follow the positions of the wheel and the displacements of the epicenter.
In a device using an anchor to an immoveable object or surface at one end thereof and an attachment to a club at the other end thereof, the variations of the radius created between the anchor and the club must be considered. From full length at address position and, preferably at waist level, this radius decreases from waist to top. Then, on the downswing, it returns to its full length while approaching the impact zone. This full length is kept until more or less at waist level on the follow-through and decreases again up to the finish position.